In the conventional gas turbine engine, an intake air is compressed by the compressor. The compressed air is supplied into combustors where it is combusted with fuel to generate high-temperature and high-pressure combustion gas. The combustion gas is supplied to a turbine where it is used as rotational energy and then discharged into the air.
Typically, the compressor casing, which is made of cast iron, needs anti-corrosion treatment because the rust created on the inner surface of the compressor casing would adhere to the surfaces of the blade wheels to degrade the performance of the compressor. Also, flaked rust may clog a passage for transporting a part of the compressed air to be used in cooling heated components in the turbine and thereby affect respective lifetimes of the components. To cope with this problem, JP 2009-523939 (A) discloses to provide an anti-corrosion coating on surfaces of the compressor casing, exposed to the air passage. According to this technique, the anti-corrosion coating is provided on portions exposed to the air passage between the radially outward flanges of the stator blade wheels mounted on the inner surfaces of the compressor casing and the seal rings (shrouds) opposing the radially outward ends of the rotor blade wheels.
The technique, however, requires the coatings on the inner surface portions of the compressor casing, which increases the manufacturing process and cost of the engine. Instead, no coating will need periodic cleanings of the inner surfaces of the compressor casing, increasing the maintenance cost.
Therefore, an object of the present invention is to provide a compressor for use in the gas turbine engine capable of preventing a creation of rust on the inner surfaces of the compressor casing without any increase of the manufacturing process.